In the drilling equipment apparatus and machine art it is conventional to assemble multiple individual lengths of longitudinal pipe (which shall also be construed broadly enough to include rods) to provide any desired resultant length of the assembly to make it possible to drill to great depths. The junction of individual elements of such drill pipe is conventionally provided by what are known in the art as tool joints and which merely comprise various types of threaded joints, or junction members, in each case including a male, exteriorly threaded, portion generally referred to as the pin, and a female, interiorly threaded portion, generally referred to as the box. The threads may be of any type, in cross-section, of any pitch, and may extend along a cylindrical interior core portion or may extend along a core portion of generally conical form, and there are a number of such conventional types and sizes of tool joints. Of course, it is requisite when assembling such a long string of drill pipe sections, or the like, to match the male threaded pin member with the proper female threaded box member and this task often requires a considerable period of time if the person doing the assembly is not already certain of the specific tool joint pin and tool joint box sizes and types to be threadedly engaged. It is precisely for the purpose of solving this prior art problem and greatly simplifying the quick, complete, and specific identification of any particular unknown tool joint pin or tool joint box that the novel apparatus of the present invention has been invented and developed as detailed hereinbelow.